Information recording device and information recording method

ABSTRACT

A laser beam from a pickup is focused on an information recording medium, such as a DVD-R/RW, to record information. When the power of the laser beam is calibrated, the laser beam emitted from the pickup is received by a light receiving unit such as an FMD. The level of the received laser beam is detected, the power ratio of the laser beam is determined based on the result, and the power of the laser beam is calibrated so that the power ratio matches a predetermined reference power ratio. This method enables information to be recorded with optimum recording characteristic because the reference power ratio shows the power ratio for recording information at the optimum characteristics.

TECHNICAL FIELD

The present invention relates to a method of optically recordinginformation onto an information recording medium.

BACKGROUND TECHNIQUE

As an information recording medium capable of optically recordinginformation, there are known a DVD-R/RW and a CD-R/RW for example, andthere exists an information recording apparatus for recording theinformation onto the information recording medium. Such the informationrecording apparatus is also called “drive apparatus”. At the time ofinformation recording, the drive apparatus irradiates, onto theinformation recording medium, a recording light such as a laser lightwith an appropriate recording power, and forms pits correspondent to therecording information onto the recording surface of the informationrecording medium. Thereby, the drive apparatus records the information.Therefore, for precise information recording, it is necessary that therecording light of an appropriate recording power is maintained.

The drive apparatus is usually shipped after the recording powercalibration in the production process. On the contrary, after theshipment, though a correction correspondent to temperature change due tocircumstances is executed, the recording power calibration is notparticularly performed. The correction correspondent to the temperaturechange is a process which corrects a current value for driving a laserdiode based on the temperature of the circumstances in which therecording drive apparatus is put and a temperature characteristic of thelaser diode loaded on the drive apparatus.

On the disc such as the CD-R/RW, the DVD-R/RW and a DVD+R/RW,information (hereinafter referred to as “optimum recordinginformation”), such as an optimum recording power value and a recordingpower ratio for performing the precise recording onto the recordingmedium, is prerecorded. It is noted that the recording power ratio is aratio of plural levels in a laser driving waveform (also referred to as“strategy”) at the time of recording the information. Therefore, basedon the optimum recording information recorded on the disc, the driveapparatus performs test recording for determining a preferable recordingcondition and actual information recording. Namely, the drive apparatusperforms the recording by driving the laser diode so that the recordingpower meets the optimum recording power value and recording power ratiorecorded on the disc.

However, even if the recording is performed on the basis of the optimumrecording information recorded on the disc, the recording laser lightactually outputted from the pickup is not always the optimum recordingpower ratio due to an error of the power calibration performed at thetime of the shipment and the temperature change in the circumferences inwhich the drive apparatus is used. In the case, the best recordingcondition cannot be obtained in the test recording, and the bestrecording characteristic cannot be obtained in the actual informationrecording. This is particularly remarkable at the time of so-calledhigh-speed recording at double, 4-times or higher speed.

DISCLOSURE OF INVENTION

The present invention has been achieved in order to solve the aboveproblems. It is an object of this invention to make it possible tocalibrate a recording power so that the recording power meets an optimumrecording power ratio without receiving effects due to a powercalibration error in a production process and temperature change causedby the circumstances.

According to one aspect of the present invention, there is provided aninformation recording apparatus including: a pickup which emits a laserlight; a light receiving unit which receives the laser light emittedfrom the pickup; and a power calibration unit which calculates a powerratio in the laser light received by the light receiving unit andperforms power calibration for calibrating a power of the laser lightemitted from the pickup so that the calculated power ratio becomesidentical to a predetermined reference power ratio.

According to another aspect of the present invention, there is providedan information recording method including: a process which receives alaser light emitted from a pickup; a process which calculates a powerratio in the laser light received by the light receiving unit; and aprocess which performs power calibration for calibrating a power of alaser light emitted from the pickup so that the calculated power ratiobecomes identical to a predetermined reference power ratio.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a functional block diagram showing a configuration of aninformation recording apparatus according to an embodiment of thepresent invention;

FIG. 2 shows a configuration of the information recording apparatusaccording to the embodiment of the present invention;

FIG. 3 is a flow chart showing an example of a power ratio calibrationprocess;

FIG. 4 shows a laser driving waveform at the time of 4-times speedrecording of a DVD-R;

FIGS. 5A to 5C show examples of a margin characteristic of a recordingpower ratio Po/Pm at the time of the 4-times speed recording of theDVD-R;

FIG. 6 is a diagram showing a definition of a distortion ratio shown inFIG. 5C;

FIGS. 7A and 7B show examples of a power margin characteristic in a casethat the recording power ratio is close to an optimum recording powerratio and in a case that the recording power ratio is not close to theoptimum recording power ratio, at the time of the 4-times speedrecording of the DVD-R;

FIG. 8 shows a laser driving waveform at the time of recording on aDVD-RW;

FIGS. 9A to 9C show examples of a margin characteristic of a recordingpower ratio at the time of double speed recording of the DVD-RW;

FIG. 10 shows an example of the power margin characteristic in a casethat the recording power ratio is identical to the optimum recordingpower ratio and in a case that the recording power ratio is notidentical to the optimum recording power ratio at the time of the doublespeed recording of the DVD-RW;

FIG. 11 shows an example of the laser driving waveform at the time ofthe 4-times speed recording of a DVD+R;

FIG. 12A shows the laser driving waveform at the time of the recordingof a CD-R, and FIG. 12B shows the laser driving waveform at the time ofthe recording of a Multi-speed CD-R;

FIG. 13 shows a flow chart of an erasing power determination processaccording to a modification; and

FIG. 14 is a configuration block diagram of a modification of theinformation recording apparatus.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

The preferred embodiments of the present invention will now be describedbelow with reference to the attached drawings. FIG. 1 is a functionalblock showing a configuration of the information recording apparatusaccording to the embodiment of the present invention. In FIG. 1, aninformation recording and reproduction apparatus 1 of this embodimentincludes a pickup 10 irradiating a recording light onto the informationrecording medium such as an optical disc, a light receiving unit 20receiving the recording light emitted from the pickup 10 and a powercalibration unit 30 detecting a power of the recording light received bythe light receiving unit 20 and calibrating the power of the recordinglight emitted from the pickup 10 to be the optimum power ratio.

The above-mentioned information recording apparatus thus constructedirradiates, onto the information recording medium such as a DVD-R/RW, aDVD+R/RW and a CD-R/RW, the laser light from the pickup 10 to record theinformation. In addition, at the time of power calibration of the laserlight, the laser light emitted from the pickup 10 is received by thelight receiving unit 20. The level of the received laser light isdetected, and based on the level, the power ratio of the laser light isdetermined. The power of the laser light is calibrated so that the powerratio of the laser light becomes identical to the predeterminedreference power ratio. The reference power ratio indicates the powerratio capable of recording the information onto the informationrecording medium with the optimum recording characteristic. Thereby, itbecomes possible that the information is recorded with the optimumrecording characteristic.

The reference power ratio may be prerecorded onto the informationrecording medium. In the case, the information recording apparatus mayinclude a reading unit which reads the reference power ratio recorded onthe information recording medium by using the pickup 10. In addition,the reference power ratio may be a power ratio in a recording mode ofthe laser light.

The reading unit can read the optimum recording power value recorded onthe information recording medium, and the power calibration unit 30 canperform the power calibration based on the optimum recording powervalue.

In addition, when test recording is performed before the actualinformation recording, the power calibration unit 30 can perform thepower calibration for at least one power value within a predeterminedpower range determined based on the optimum recording power value.

Additionally, the power calibration unit 30 preferably performs thepower calibration in a state that the pickup 10 is positioned in an areaother than an information recording area of the information recordingmedium or in a state that the pickup 10 is positioned in a testrecording area of the information recording medium. Thereby, it can beprevented that the recording is performed in error in the originalinformation recording area of the information recording medium duringthe power calibration.

The above-mentioned light receiving unit 20 may be a front monitor unitin the pickup 10. In the case, by using the internal configuration ofthe pickup 10, the power of the laser light can be easily detected. Inaddition, the light receiving unit 20 may be a light detector disposedon the surface on which the information recording medium is disposed. Inthe case, the light receiving unit 20 can detect the same laser lightpower as the power irradiated onto the disc by the light receiving unit20.

In addition, the power ratio may be a ratio of different level portionsincluded in the laser driving waveform for the information recording.For example, the recording power ratio may be the ratio of the level ofa top pulse portion to the level of an intermediate pulse portion in thelaser driving waveform at the time of the information recording of theDVD-R. Similarly, as for the DVD-RW, the DVD+R, and the DVD+RW, thepower ratio may be the ratio of the different level portions in thelaser driving waveform at the time of the information recording.

Embodiment

Next, the description will be given of preferred embodiments of thepresent invention with reference to drawings.

[Configuration of Information Recording Apparatus]

FIG. 2 shows a configuration of the information recording apparatusaccording to a first embodiment of the present invention. In FIG. 2, theinformation recording apparatus 1 records the information onto anoptical disc 2 such as the CD-R/RW, the DVD-R/RW and the DVD+R/RW, andincludes a spindle motor 3, the pickup 10, amplifiers 4 and 5, a servocontrol unit 6, a recording power detecting unit 31 and a system controlunit 32.

The spindle motor 3 rotates the optical disc 2 at the predeterminedspeed based on the control signal supplied from the servo control unit6. The pickup 10 includes an LD (Laser Diode) 13 serving as a lightsource of the recording light, an LD driver 11 driving the LD, a frontmonitor diode (FMD) 21 functioning as the light receiving unit and anoptical system (not shown). The LD driver 11 supplies a driving currentto the LD 13 based on an LD control signal 17 supplied from the systemcontrol unit 32, and makes the LD 13 emit a laser light L for recordingand erasing the information via the optical system.

In addition, the pickup 10 receives the laser light reflected on theoptical disc 2 by the light detector (not shown), and generates a lightdetecting signal 15 being the electrical signal correspondent to thelight amount to output it to the amplifier 4. On the contrary, the FMD21 receives the laser light emitted from the LD 13, and generates alaser power detecting signal 16 correspondent to the light amount tooutput it to the amplifier 5.

As the need arises, the amplifier 4 amplifies or attenuates the lightdetecting signal 15 to supply it to the servo control unit 6. Based onthe light detecting signal 15, the servo control unit 6 executes variousservo control, such as the tracking servo, the focus servo and thespindle servo. Concretely; the servo control unit 6 is controlled by thecontrol signal 14 from the system control unit 32. The servo controlunit detects various kinds of servo errors based on the light detectingsignal 15, and generates a servo control signal 18 to supply it to thepickup 10 and the spindle motor 3, thereby to execute various kinds ofservo controls.

The amplifier 5 amplifies the laser power detecting signal 16 outputtedfrom the FMD 21 to supply it to the recording power detecting unit 31.The recording power detecting unit 31 includes a sample hold circuit, apeak hold circuit or a bottom hold circuit and the like, for example.The recording power detecting unit 31 detects the laser power at apredetermined timing from the laser power detecting signal 16 to supplyit to the system control unit 32 as a detected laser power value 19.

The system control unit 32 is constructed by a micro computer and thelike. Based on optimum recording information recorded on the opticaldisc 2 subjected to recording and the detected laser power value 19, thesystem control unit 32 generates the LD control signal 17 to supply itto the LD driver 11. Thereby, the power of the laser light emitted fromthe LD 13 is optimized.

[Power Ratio Calibration Process]

Next, the description will be given of the control executed in thesystem control unit 32 in detail. The system control unit 32 performspower ratio calibration. The optimum recording information is recordedon the optical disc 2 such as the DVD-R/RW so that the recording ontothe optical disc 2 can be performed in the optimum condition. Theoptimum recording information is information defining the recordingpower necessary for performing the recording onto the optical disc 2with the optimum recording characteristic. The detail explanation willbe given later. However, in the case of the DVD-R, as shown in FIG. 4,the recording data equal to or larger than 5 T is recorded by drivingthe LD by the substantially recessed-shape laser driving waveform(strategy). In this case, the laser driving waveform is prescribed by alevel Po of a top pulse portion 201 and a level Pm of an intermediatepulse portion 202. On the disc of the DVD-R, the optimum recording powervalue (in this example, the value of the level Po of the top pulseportion 201, e.g., 12 mW) and the optimum recording power ratioPr(=Po/Pm) are recorded as the optimum recording information. Namely,information that “if the laser driving waveform is generated in order tomake the level Po of the top pulse portion meet 12 mW and the recordingpower ratio Pr=Po/Pm and the recording is performed, the recording canbe performed with the optimum recording characteristic” is recorded onthe DVD-R.

Based on the optimum recording information, first, the system controlunit 32 generates the laser driving waveform, and actually drives the LD13 to emit the laser light. The emitted laser light is received by theFMD 21. The laser power is detected by the recording power detectingunit 32 to be supplied to the system control unit 32 as the detectedlaser power value 19. The system control unit 32 calculates therecording power ratio Pr=Po/Pm based on the detected laser power valuesof the top pulse portion 201 and the intermediate pulse portion 202 inthe laser driving waveform shown in FIG. 4. Then, the system controlunit 32 generates the LD control signal 17 and controls the LD driver 11so that the calculated recording power ratio becomes equal to theoptimum recording power ratio read from the optical disc 2. In such themethod, the feedback control is executed so that the laser poweractually emitted from the LD 13 becomes the optimum recording powerratio recorded on the optical disc 2. This is a power ratio calibrationprocess according to the present invention.

Here, the DVD-R is cited as an example of the optical disc 2, and it isdescribed that the optimum recording information includes the optimumrecording power value=the level Po of the top pulse portion and theoptimum recording power ratio Pr(=Po/Pm). However, the optimum recordinginformation used in the power ratio calibration process is naturallydifferent dependently on the kinds of discs. This will be describedlater.

Next, the description will be given of an example of the power ratiocalibration process. FIG. 3 is a flow chart showing one example of thepower ratio calibration process. This process is realized by making thesystem control unit 32 shown in FIG. 2 execute the program prepared inadvance.

First, the system control unit 32 detects whether or not the opticaldisc 2 is set in the information recording apparatus 1 (step S10). Whendetecting the optical disc 2 being set, the system control unit 32obtains the optimum recording information from the optical disc 2, andtemporarily stores it therein (step S11). The optimum recordinginformation includes the optimum recording power value and the optimumrecording power ratio for example, as described above.

Next, the system control unit 32 determines whether or not the recordingpreparation is completed (step S12). This can be determined based on astate that each component of the information recording apparatus 1including the pickup 10 can perform a recording operation and a statethat a user inputs a recording instruction to the information recordingapparatus 1, for example.

Next, the system control unit 32 positions the pickup 10 in the testrecording (test writing) area with the servo control by the servocontrol unit 6 maintained, or moves the pickup 10 to the area incapableof recording, i.e., the disc innermost circumference or the discoutermost circumference, with the servo control by the servo controlunit 6 turned off (step S13). Namely, the system control unit 32positions the pickup 10 in the area other than the information recordingarea of the disc. It is necessary to emit the laser light from the LD 13at the time of the calibration of the power ratio. Therefore, it has tobe prevented that the useless data recording is performed in theoriginal information recording area on the disc by the laser light.Therefore, the power calibration process is performed in the state thatthe pickup 10 is positioned in the test area or in the area incapable ofrecording at the disc inner or outer circumference.

When the pickup 10 is positioned in the area other than the informationrecording area of the disc, the system control unit 32 next determineswhether or not to perform the test writing before the actual informationrecording (step S14). This can be determined by referring to the settinginformation indicating whether or not the information recordingapparatus 1 is set to such a mode that the test recording is performedbefore the actual recording, for example.

When the test recording is performed (step S14; Yes), the system controlunit 32 performs the above-mentioned power ratio calibration with atleast one power within the power range for performing the test recording(step S15). Normally, the test recording is performed by changing therecording power within the predetermined power range, and based on theresult, the optimum recording power is determined. Therefore, the systemcontrol unit 32 performs the power ratio calibration for at least one orpreferably several recording power value(s) within the predeterminedpower range for performing the test recording. In this case, thepredetermined power range for performing the test recording can bedetermined by setting the optimum recording power value pre-read fromthe optical disc 2 at the center.

On the other hand, when the test recording is not performed (step S14;No), the system control unit 32 performs the power ratio calibration atthe optimum recording power value pre-read from the optical disc 2.Namely, in this case, the power ratio calibration is performed only forthe one recording power value.

In such the way, the power ratio calibration is performed for at leastone recording power value. By performing the power ratio calibration,the laser power actually emitted from the LD 13 of the pickup 10satisfies the condition defined by the optimum recording information.Therefore, when the test recording is performed, it becomes possiblethat the test recording with high accuracy is performed by using therecording power after performing the power ratio calibration in stepS15. In addition, when the test recording is not performed and theactual information recording is performed, by the recording power afterperforming the power ratio calibration in step S16, the recording ontothe optical disc 2 can be performed with the optimum recordingcharacteristic.

[Optimum Recording Information on Various Kinds of Discs]

Next, it will be explained, for each disc, which value is used as theoptimum recording information in the above-mentioned power ratiocalibration process respectively, when the present invention is appliedto a reproduction apparatus of various kinds of discs.

(1) DVD-R

FIG. 4 shows the laser driving waveform at the time of the 4-times speedrecording of the DVD-R. In the 4-times speed recording of the DVD-R, therecording data of 3 T and 4 T is recorded by the single laser drivingwaveform shown on the left side of FIG. 4, and the recording data equalto or larger than 5 T is recorded by the laser driving waveform in asubstantial recess shape shown on the right side of FIG. 4. When thelevel of the top pulse portion 201 and the last pulse portion 203 of thelaser driving waveform equal to or lager than 5 T is prescribed as Poand the level of the intermediate pulse portion 202 is prescribed as Pm,the value of the optimum recording power ratio: Pr=Po/Pm is recorded onthe DVD-R as the optimum recording information. Therefore, when thepresent invention is applied to the DVD-R, the power ratio calibrationprocess is executed so that the recording power ratio obtained from thelaser light actually emitted from the LD 13 becomes identical to thevalue of the optimum recording power ratio: Pr=Po/Pm. It is noted thatPb is the bias level.

FIGS. 5A to 5C show an example of a margin characteristic of therecording power ratio: Pr=Po/Pm at the time of the 4-times speedrecording of the DVD-R. In this example, the optimum recording powerratio prerecorded on the DVD-R is the value about 1.45.

First, parameters examined below will be briefly explained. “Jitter” isa value indicating a fluctuation degree of rise-up and fall-down edgesof a binarized reproduction signal, with respect to a PLL clockgenerated from the binarized reproduction signal. As the clock jitter ishigher, the quality of the reproduction signal is worse. Conversely, asthe clock jitter is lower, the quality of the reproduction signal isbetter. According to a DVD-R standard book, the jitter value: smallerthan 8.0% is necessary. “Asymmetry” is a value indicating a shift degreeof the magnitude center between the minimum recording mark (3 T mark)and the maximum recording mark (14 T mark), and according to the DVD-Rstandard book, the asymmetry: −0.05 to 0.15 is necessary.

“Modulation (I14H)” is a value indicating a ratio (I₁₄/I_(14H)) of amagnitude I₁₄ of the reproduction signal correspondent to the maximumrecording mark to a difference I_(14H) between the peak value and zerolevel of the reproduction signal correspondent to the maximum recordingmark (14 T mark) and. According to a DVD-R standard book, themodulation: equal to or larger than 0.60 (60%) is necessary.

FIG. 5A shows a relation between the recording power ratio (Po/Pm ratio)and the jitter. It is understood that as the recording power ratio isshifted with respect to the optimum value, the jitter becomes worse.FIG. 5B shows a relation among the recording power ratio, the asymmetryand the modulation. From FIG. 5B, it is understood that when therecording power ratio changes, the value of the asymmetry maintainsalmost constant, and when the power ratio is small, the modulation ofthe recording signal becomes large. This may give an adverse effect toROPC (Running Optimum Power Control), which is not preferred. Inaddition, when the power ratio becomes large, the modulation becomessmall, and S/N becomes worse.

FIG. 5C shows a relation between the recording power ratio and adistortion ratio of the recording waveform. It is understood that whenthe recording power ratio becomes larger than the optimum value, thedistortion ratio becomes large. It is noted that the distortion ratio ofthe recording waveform shown in FIG. 5C is defined as shown in FIG. 6.FIG. 6 shows an example of the reproduction waveform of the recordingsignal, and a ratio of a distortion amount B to a magnitude A of thereproduction waveform is defined as the distortion ratio shown in FIG.5C.

In addition, FIGS. 7A and 7B show the power margin characteristic incases that the recording power ratio: Pr=Po/Pm is close to and not closeto the optimum recording power ratio at the time of the 4-times speedrecording of the DVD-R. Specifically, FIG. 7A shows the variation of thejitter in a case that the recording power Pw is varied in a conditionthat the recording power ratio is set to the optimum value (Po/Pm=1.45)and the other value (Po/Pm=1.35) and the recording power ratio ismaintained constant. FIG. 7B shows the variation of the modulation inthe case. From FIG. 7A, it is understood that when the recording powerratio is shifted with respect to the optimum value, the minimum value ofthe jitter increases. In addition, it is understood that the recordingpower Pw necessary for obtaining the minimum value of the jitter alsoincreases. From FIG. 7B, it is understood that when the recording powerratio is small, the modulation becomes large and the variation ratio(i.e., the tilt of the graph) with respect to the power of themodulation becomes small. Thus, when the modulation during theinformation recording is monitored and the ROPC control is executed, theaccuracy becomes worse.

As described above, when the recording power ratio is shifted withrespect to the optimum recording power ratio, there appear various kindsof adverse effects as follows: the jitter increases, the modulationdecreases, the distortion becomes large, the accuracy of the ROPC maydecrease. Therefore, it is understood that, in order to perform therecording with the optimum recording characteristic, it is effectivethat the power calibration is performed so that the recording powerratio becomes identical to the optimum recording power ratio by thepower ratio calibration process.

(2) DVD-RW

Next, the description will be given of the optimum recording informationfor the DVD-RW. FIG. 8 is the laser driving waveform at the time of therecording of the DVD-RW. The laser driving waveform of the DVD-RWincludes the recording power level Pw, the erasing power level Pe andthe bias power level Pb. Onto the DVD-RW, the optimum value of the ratioε (=Pe/Pw) of the erasing power level Pe to the recording power level Pwis recorded as the optimum recording power ratio. Thus, in the case ofthe DVD-RW, the above-mentioned power ratio calibration process isperformed for the recording power ratio ε.

It is noted that the laser driving signal of the similar waveform isused for the information recording, as for the CD-R and the DVD+RW.Therefore, the power ratio calibration process may be executed for therecording power ratio ε, similarly to the DVD-RW.

FIGS. 9A to 9C are examples of the margin characteristic of therecording power ratio ε at the time of double speed recording of theDVD-RW. FIG. 9A shows a relation between the recording power ratio ε andthe jitter, FIG. 9B shows a relation between the recording power ratio εand the asymmetry, and FIG. 9C shows a relation between the recordingpower ratio ε and the modulation. It is noted that the optimum recordingpower ratio is ε=about 0.52 (indicated by a straight line 210 in FIGS.9A to 9C) in this example. From FIG. 9A, it is understood that when therecording power ratio ε is shifted with respect to the optimum recordingpower ratio, the jitter becomes worse. From FIG. 9B, it is understoodthat when the recording power ratio ε is shifted with respect to theoptimum recording power ratio, the asymmetry varies. Additionally, fromFIG. 9C, it is understood that when the recording power ratio ε isshifted with respect to the optimum recording power ratio, themodulation varies.

As described above, when the recording power ratio ε is smaller than theoptimum recording power ratio, the increasing amount of the jitter issmall. But the asymmetry becomes deep, and the modulation is saturated.Namely, the recording power becomes too large, which gives the adhesiveeffect to the repetitive recording characteristic of the DVD-RW. Thatis, a number capable of rewriting decreases. On the contrary, when therecording power ratio ε is larger than the optimum recording powerratio, the asymmetry becomes shallow, and the jitter becomes worse.

FIG. 10 shows examples of the power margin characteristic in a case thatthe recording power ratio ε (ε=0.52) is identical to the optimumrecording power ratio and in a case that the recording power ratio ε isnot identical to the optimum recording power ratio (ε=0.60) at the timeof the double speed recording of the DVD-RW. In FIG. 10, the horizontalaxis shows the recording power value Pw, and the vertical axis shows thejitter. As understood with reference to FIG. 10, in-the case that therecording power ratio ε is not identical to the optimum recording powerratio, the minimum jitter value becomes large in comparison with thecase that the recording power ratio ε is identical to the optimumrecording power ratio.

Like this, in the DVD-RW, it is understood that by making the recordingpower ratio ε identical to the optimum recording power ratio (about 0.52in this embodiment), the optimum recording characteristic can beobtained.

(3) DVD+R

FIG. 11 shows an example of the laser driving waveform at the time ofthe 4-times speed recording of the DVD+R. The recording power forforming the recording mark equal to or lager than 5 T is Pp, therecording power for forming the recording mark of 4 T is Pp+ΔPp (4 T),and the recording power for forming the recording mark of 3 T is Pp+ΔPp(3 T). On the DVD+R, the recording power Pp shown in FIG. 11 and theratio of the recording power at the time of recording 3 T mark and 4 Tmark to the recording power Pp. Namely, the recording power ratio: ΔPp(3T)/Pp and ΔPp(4 T) /Pp are recorded as the optimum recordinginformation. Therefore, in the case of the DVD+R, the above-mentionedpower ratio calibration process is executed for the recording powerratios.

(4) CD-R

FIG. 12A is the laser driving waveform at the time of the recording ofthe CD-R, and FIG. 12B is the laser driving waveform at the time of therecording of a Multi-speed CD-R. On the CD-R, the ratio of the recordingpower ΔPw to the recording power Pw in FIGS. 12A and 12B is recorded asthe optimum recording information. Thus, in the case of the CD-R, theabove-mentioned power ratio calibration process is executed for therecording power ratio (ΔPw/Pw)

[Modification 1]

Next, the description will be given of a modification of theabove-mentioned information recording apparatus. The modificationapplies the above-mentioned power ratio calibration process to thedetermination of the erasing power. As for the disc on which theinformation is repeatedly recorded, such as the DVD-RW, the DVD+RW andthe CD-RW, at the time of rewriting the information similarly to thetime of the recording, by performing the test recording after performingthe power ratio calibration, the recording power and the erasing powercan be determined. By erasing the recording information with the erasingpower thus determined, the appropriate erasing can be performed.

FIG. 13 shows a flowchart of the erasing power determination processaccording to this modification. This process is realized by making thesystem control unit 32 shown in FIG. 2 execute the program prepared inadvance.

First, the system control unit 32 detects whether or not the opticaldisc 2 is set in the information recording apparatus 1 (step S20). Whendetecting the optical disc 2 being set, the system control unit 32obtains the optimum recording information from the optical disc 2 totemporarily store it therein (step S21). The optimum recordinginformation includes the optimum recording power value and the optimumrecording power ratio, as described above.

Next, the system control unit 32 determines whether or not erasing theinformation is prepared (step S22). Next, the system control unit 32maintains the servo control by the servo control unit 6 and positionsthe pickup 10 in the test recording area, or makes the servo control bythe servo control unit 6 turned off and moves the pickup 10 to the areaincapable of recording at the disc innermost circumference or to thedisc outermost circumference (step S23). Similarly to the case of thepower calibration process shown in FIG. 2, by positioning the pickup 10in the area other than the information recording area of the disc, itcan be prevented that the useless data recording is performed in theoriginal information recording area on the disc by the laser lightduring the erasing power determination process.

Next, the system control unit 32 performs the above-mentioned powerratio calibration with at least one power within the power range for thetest recording (step S24). Thus, the power ratio calibration isperformed for at least one power value. By performing the power ratiocalibration, the laser power actually emitted from the LD of the pickup10 satisfies the condition defined by the optimum recording information.

Next, the system control unit 32 performs the test recording with therecording power after performing the power ratio calibration, anddetermines the recording power and the erasing power (step S25).Thereby, it becomes possible that the information is erased with theappropriate power.

[Modification 2]

Next, another modification will be explained. This modification is amodification of the light receiving unit 20 receiving the laser lightemitted from the LD, and FIG. 14 shows a configuration thereof. In FIG.14, the same reference numerals are given to the same components asthose of the information recording apparatus 1 shown in FIG. 2.

In the above-mentioned embodiment, the FMD is used as the detecting unitof the recording power. However, as shown in FIG. 14, a detector 22 maybe provided at a position on the outer circumferential side of theoptical disc 2 so that the detector 22 does not contact the optical disc2, and may be used as the light receiving unit 20, for example. Likethis, when the detector 22 is provided at the position on the outercircumferential side of the optical disc 2 on the same surface as theoptical disc 2 and the output laser light of the LD 13 is detected,unlike the FMD, the power of the laser light actually irradiated ontothe optical disc 2 can be detected by the detector 22.

As explained above, in the present invention, the information recordingapparatus includes the pickup emitting the laser light, the lightreceiving unit receiving the laser light emitted from the pickup such asthe FMD or the detector, the recording power detecting unit and thesystem control unit determining the power ratio in the laser lightreceived by the FMD or the detector and calibrating the power of thelaser power emitted from the pickup in order to make the determinedpower ratio identical to the predetermined reference power ratio.Therefore, by the power ratio calibration, in all the drive apparatus,it becomes possible to perform the actual information recording and testrecording with the appropriate power ratio in any temperaturecircumstance. Moreover, it becomes possible to prevent an error of thepower calibration at the time of the shipment from a factory and thechange of the power ratio caused due to variation of differentiatingquantization efficiency of the LD by the temperature change. As aresult, the optimum recording characteristic can be obtained. This isparticularly effective at the time of the recording with the increasedspeed at which the accuracy is necessary. In addition, since not powerabsolute value calibration but the power ratio calibration is performed,a special system and a complicated technique are unnecessary.

INDUSTRIAL APPLICABILITY

This invitation is applicable to an apparatus for recording andreproducing the information onto and from various kinds of optical discssuch as the DVD-R/RW, the CD-R/RW, the DVD+R/RW.

1-11. (canceled)
 12. An information recording apparatus comprising: apickup which emits a laser light; a light receiving unit which receivesthe laser light emitted from the pickup; and a power calibration unitwhich calculates a recording power ratio which is a ratio of lightreceiving levels detected by the light receiving unit correspondent todifferent emitting level portions of the laser light and performs powercalibration for calibrating a recording power of the laser light emittedfrom the pickup so that the calculated recording power ratio becomesidentical to an optimum recording power ratio.
 13. The informationrecording apparatus according to claim 12, wherein a driving waveform ofthe laser light includes a top pulse and a last pulse having a firstlevel respectively and an intermediate pulse portion positioned betweenthe top pulse and the last pulse and having a second level smaller thanthe first level, and wherein the recording power ratio is a ratio of alight receiving level of the light receiving unit correspondent to thetop pulse or the last pulse to a light receiving level of the lightreceiving unit correspondent to the intermediate pulse portion.
 14. Theinformation recording apparatus according to claim 12, wherein a drivingwaveform of the laser light includes a recording power level, an erasingpower level and a bias power level, and wherein the recording powerratio is a ratio of the light receiving level correspondent to the laserlight in the erasing power level to the light receiving levelcorrespondent to the laser light in the recording power level.
 15. Theinformation recording apparatus according to claim 12, furthercomprising a reading unit which reads the optimum recording power ratiorecorded on an information recording medium by using the pickup.
 16. Theinformation recording apparatus according to claim 12, wherein the powercalibration unit performs the recording power calibration for at leastone power value within a predetermined power range determined based onthe optimum recording power value when test recording is performedbefore actual information recording.
 17. The information recordingapparatus according to claim 12, wherein the power calibration unitperforms the power calibration in a state that the pickup is positionedat an area other than an information recording area of the informationrecording medium.
 18. The information recording apparatus according toclaim 12, wherein the power calibration unit performs the powercalibration in a state that the pickup is positioned in a test recordingarea of the information recording medium.
 19. The information recordingapparatus according to claim 12, wherein the light receiving unit is afront monitor unit in the pickup.
 20. The information recordingapparatus according to claim 12, wherein the light receiving unit is alight detector disposed on a surface on which the information recordingmedium is disposed.
 21. An information recording method comprising: aprocess which receives a laser light emitted from a pickup; a processwhich calculates a recording power ratio which is a ratio of lightreceiving levels detected by the light receiving process correspondentto different emission level portions of the laser light; and a processwhich performs a power calibration for calibrating a recording power ofa laser light emitted from the pickup so that the calculated recordingpower ratio becomes identical to an optimum recording power ratio.